The important part.... talk about fucked up.
The Hughes Amendment
The restrictions on full-auto firearms are a result of the Hughes Amendment (99th Congress, H.AMDT.777). The amendment prohibited the general public from possessing fully-auto firearms manufactured after May 19, 1986. Rep. William Hughes (D-N.J.) proposed the amendment late in debate and at night when most of the members of the House were gone. Rep. Charles Rangel (D-N.Y.), a long proponent of gun control, was presiding over the House at that time and a voice vote was taken. Despite the fact that the bill appeared to fail, Rep. Rangel declared the amendment approved and it was incorporated into House Bill 4332. Once passing the House, H.R.4332 was incorporated in its entirety into S.49. The Senate passed the final S.49 on April 10, 1986 by voice vote and it was signed by the President on May 19, 1986.
More information is available in the July 1986 issue of the American Rifleman. It is not available online.